The primary mission of the Methodology core is to assure the validity of study findings that eventually will be disseminated in manuscripts and public presentations. Specific aims include: 1. To provide Project investigators a centralized resource for statistical and epidemiologic collaboration and consultation, coordinated protocol development, data management, and data analysis. 2. To vigorously support scientific communication among Project investigators as well as communication of research findings to persons outside the team through formal and informal seminars and electronic communication. 3. To ensure the highest quality scientific research by organizing formal protocol review, study monitoring, and manuscript review committees that will promote rigorous biostatistical and epidemiological methods. Formal oversight ensures that valid, efficient, and ethical research is conducted. 4. To serve as an educational resource for issues related to study design and analysis. The Methodology Core program will accomplish this mission by providing comprehensive statistical, epidemiologic, measurement, data management, and scientific oversight throughout the course of each Project. The Core investigators will apply sound statistical principles to study planning, monitoring, and data analysis, as well as educate musculoskeletal researchers in the University community with respect to these issues. The Methodology Core will provide biostatistical expertise in the design and conduct of clinical trials (Project 1), planning, execution, and interpretation of statistical analyses for randomized and observational studies (Projects 1-4), and comprehensive data management capabilities (Projects 1-4).